Ammonia Assimilation in Methanobacterium Formicium and Some Properties of Glutamine Synthetase

Since Methanobacterium formicium grew in the presence of low ammonia concentration it was thought likely that GS/GOGAT system for ammonia assimilation would be present in cell extract of M. formicium. Cell free extracts of M. formicium were assayed by -glutamyl transferase method. The cell free extracts preparation showed significant glutamine synthetase activity. Optimum pH of glutamine synthetase was found to be 8.8. The enzyme was partially oxygen sensitive and temperature sensitive. Glutamate synthase (GOGAT) activity could not be detected in cell free extracts of M. formicium. Glutamate dehydrogenase activity was present in cells grown with high concentration (3.4 mM) of ammonia.